This invention relates to a disposable undergarment and more particularly to such undergarment including a disposable diaper, a training pant and an incontinent pant.
Japanese Patent Application Publication No. 1996-196559A describes the disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent panel. The panel consisting of a body fluid absorbing/holding layer comprising fluff pulp in a content less than 70% by weight and high absorption polymer particles in a content of 30% by weight or higher and a fibrous assembly layer placed upon the top surface of the absorbing/holding layer. In the diaper of prior art, the absorbing/holding layer and the fibrous assembly layer are integrally covered with tissue paper so that substantially entire contacting surfaces of these absorbing/holding layer, fibrous assembly layer and tissue paper are intermittently bonded together by means of hot melt adhesive. This diaper of prior art is claimed to ensure that these absorbing/holding layer, fibrous assembly layer and tissue paper can be kept in close contact one with another even if the diaper is distorted.
The fibrous assembly layer certainly has a function to prevent the absorbing/holding layer from getting out of its initial shape. However, the absorbing/holding layer and the fibrous assembly layer are bonded to each other merely over their contacting surfaces, so that the regions of these layers except the contacting surfaces are apt to get out of their shapes. If the non-bonded region of the absorbing/holding layer gets out of the shape as the panel is deformed due to movement of a wearer, it is apprehended that the absorbing/holding layer might be separated from the fibrous assembly layer and a rapid absorption of body fluids in the panel might be obstructed.
It is an object of this invention to provide a disposable undergarment designed so as to prevent the body fluid absorbing/holding layer from getting out of its initial shape and thereby to ensure desirably rapid absorption of body fluids in the panel.
According to this invention, there is provided a disposable undergarment comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent panel disposed between the top- and backsheets, wherein the panel comprises a body fluid absorbing/holding layer formed with a mixture of fluff pulp, high absorption polymer particles and heat-sealable synthetic resin fibers and a nonwoven fabric layer made of heat-sealable synthetic resin fibers placed upon at least one of upper and lower surfaces of the body fluid absorbing/holding layer and wherein the absorbing/holding layer and the nonwoven fabric layer are integrally covered with and bonded to a water-pervious sheet.
According to this invention is the heat-sealable synthetic resin fibers contained in the absorbing/holding layer are heat-sealed with the nonwoven fabric layer over contacting surfaces of the absorbing/holding layer and the nonwoven fabric layer.
According to one embodiment of this invention, the absorbing/holding layer is formed on its surface opposed to the nonwoven fabric layer with a plurality of depressions each extending in a thickness direction thereof and the nonwoven fabric layer is partially engaged with the depressions so that the heat-sealable synthetic resin fibers contained in the absorbing/holding layer are heat-sealed with the nonwoven fabric layer over contacting surfaces of the absorbing/holding layer and the nonwoven fabric layer in the depressions.
According to another embodiment of this invention, the nonwoven fabric layer has a tear strength higher than that of the absorbing/holding layer.
According to still another embodiment of this invention, the absorbing/holding layer comprising the fluff pulp in a content of 15-67% by weight, the high absorption polymer grains in a content of 30-70% by weight and the heat-sealable synthetic resin fibers in a content of 3-15% by weight.
According to further another embodiment of this invention, the heat-sealable synthetic resin fibers contained in the absorbing/holding layer as well as the heat-sealable synthetic resin fibers forming the nonwoven fabric layer have been previously treated to have hydrophilicity.